Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging

Timothy G. Lach; Thak Sang Byun

doi:10.1007/978-3-030-04639-2_125

Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging

Timothy G. Lach, Thak Sang Byun

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

1 Scopus citations

Abstract

Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M ₂₃ C ₆ carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.

Original language	English
Title of host publication	Minerals, Metals and Materials Series
Publisher	Springer International Publishing
Pages	1859-1868
Number of pages	10
ISBN (Print)	9783030046385, 9783030046392, 9783319515403, 9783319651354, 9783319728520, 9783319950211
DOIs	https://doi.org/10.1007/978-3-030-04639-2_125
State	Published - 2019
Externally published	Yes
Event	18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors 2019 - Boston, United States Duration: Aug 18 2019 → Aug 22 2019

Publication series

Name	Minerals, Metals and Materials Series
ISSN (Print)	2367-1181
ISSN (Electronic)	2367-1696

Conference

Conference	18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors 2019
Country/Territory	United States
City	Boston
Period	08/18/19 → 08/22/19

Funding

This research was sponsored by U.S. Department of Energy/Office of Nuclear Energy through Light Water Reactor Sustainability R&D Program and International Nuclear Energy Research Initiative (I-NERI) Program. Pacific Northwest National Laboratory is operated by Battelle Memorial Institute for the U.S. Department of Energy under Contract No. DEAC05-76RL01830. APT and FIB/SEM were performed at PNNL’s Environmental Molecular Sciences Laboratory, a Department of Energy—Office of Biological & Environmental Research national scientific user facility.

Funders	Funder number
I-NERI
Light Water Reactor Sustainability R&D Program and International Nuclear Energy Research Initiative
U.S. Department of Energy	DEAC05-76RL01830
Battelle
Office of Nuclear Energy

Keywords

Duplex stainless steel
G-phase precipitation
Solute segregation
Spinodal decomposition
Thermal aging degradation

Access to Document

10.1007/978-3-030-04639-2_125

Cite this

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title = "Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging",

abstract = " Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M 23 C 6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.",

keywords = "Duplex stainless steel, G-phase precipitation, Solute segregation, Spinodal decomposition, Thermal aging degradation",

author = "Lach, {Timothy G.} and Byun, {Thak Sang}",

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year = "2019",

doi = "10.1007/978-3-030-04639-2_125",

language = "English",

isbn = "9783030046385",

series = "Minerals, Metals and Materials Series",

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Lach, TG & Byun, TS 2019, Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging. in Minerals, Metals and Materials Series. Minerals, Metals and Materials Series, Springer International Publishing, pp. 1859-1868, 18th International Conference on Environmental Degradation of Materials in Nuclear Power Systems – Water Reactors 2019, Boston, United States, 08/18/19. https://doi.org/10.1007/978-3-030-04639-2_125

Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging. / Lach, Timothy G.; Byun, Thak Sang.
Minerals, Metals and Materials Series. Springer International Publishing, 2019. p. 1859-1868 (Minerals, Metals and Materials Series).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › peer-review

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AU - Lach, Timothy G.

AU - Byun, Thak Sang

PY - 2019

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N2 - Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M 23 C 6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.

AB - Thermal aging degradation of cast austenitic stainless steels (CASS) was studied by electron microscopy to understand the mechanisms for thermal embrittlement potentially experienced during extended operations of light water reactor coolant systems. Four CASS alloys—CF3, CF3M, CF8, and CF8M—were thermally aged up 1500 h at 330 and 400 °C, and the microstructural evolution of the material was characterized by analytical aberration-corrected scanning transmission electron microscopy. The primary microstructural and compositional changes during thermal aging were spinodal decomposition of the δ-ferrite into α/α′, precipitation of G-phase in the δ-ferrite, segregation of solute to the austenite/ferrite interphase boundary, and growth of M 23 C 6 carbides on the austenite/ferrite interphase boundary. These changes were shown to be highly dependent on aging temperature and chemical composition, particularly the amount of C and Mo. A comprehensive model is being developed to correlate the microstructural evolution with mechanical behavior and simulation.

KW - Duplex stainless steel

KW - G-phase precipitation

KW - Solute segregation

KW - Spinodal decomposition

KW - Thermal aging degradation

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Y2 - 18 August 2019 through 22 August 2019

ER -

Microstructural evolution of cast austenitic stainless steels under accelerated thermal aging

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